Transcript FDG PET imaging

Tumor Imaging
We have a lot of selections for Tumor
Imaging
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Tumor is more metabolic active.
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Tumor has specific receptors.
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131I-MIBG, 131I-anti-AFP-MoAb
Tumor can cause function and structure changes.
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18F-FDG, 18F-FLT, 11C-acetate, 11C-cholin, 201Tl,
99mTc-MIBI.
BBB destruction, 99mTc-PMT
Tumor has specific gene expressions
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antisense imaging
18F-FDG PET
Pheochromocytoma of right adrenal gland
Bone metastasis of malignant tumor
Imaging for BBB Destruction
Objectives of This Part
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FDG PET imaging
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mechanism, imaging agent, image interpretation,
clinical indications and usage.
67Ga imaging
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imaging agent, image interpretation, clinical
indications and usage.
Importance: ***, **, *
FDG PET imaging
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Imaging agent: 18F-FDG
Imaging instrument: PET/CT or PET
Imaging procedure:
starvation for over 6h
 18F-FDG injection
 wait 40-50 min
 acquisition on PET/CT
 image reconstruction
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Molecular Mechanism
Tumor Cell
Vascular
Glycogen
18FDG-1-P
Hexokinase
K1
18FDG
18FDG-6-
K3
18FDG
K2
18FDG-6P
K4
Glucose-6phosphatase
phosphogluconolactone
18F-fru-6-P
Glucose
transporter
protein
Glycolysis
HMP
shunt
Molecular Mechanism
Normal Image
Coronal images of PET
CT, PET and fusion image
Quantitative Parameters of PETFDG Response
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Standardized uptake value (SUV)
Uptake in tumor, normalized for dose injected and
weight of the patient
 Obtained as primary response parameter on every
lesion
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SUV =
(decay corrected dose/cc of tumor)
(injected dose/patient weight (g))
Clinical Indications
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Early detect and differentiate tumor.
Tumor staging and restaging.
Define tumor scope, especially for radiotherapy
planning.
Therapy response monitoring.
Early differentiate regression or radiation
necrosis.
Lead to correct treatment, save medical expenses.
FDG PET could detect tumors in
their early stage and can be used
for tumor screen
Gastric carcinoma found in FDG PET tumor screen
FDG PET can differentiate
benign and malignant lesion
more effectively.
Carcinoma of gallbladder
Carcinoma of rectum
nasopharyngeal carcinoma
Lymphoma
Post operative scar of left lung
Brain Tumor CP 696483
High Grade recurrence post RT
PET FDG TRANSAXIAL
5 Oct 2000
T-1 POST Gd
FDG PET can stage tumor more
accurately
Lymph node metastasis of lung
carcinoma，CT is negative，but is
positive in PET
FDG PET can monitoring early
therapeutic response and predict
outcome.
after chemo
Before
Chemo
SUV=4.6
Gallium-67 for Infection /
Inflammation
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produced by cyclotron.
The half life of gallium-67 is 78 hours.
decays by electron capture.
Gallium-67 photopeaks
Energy
Abundance
93 keV
40%
184 keV
20%
300 keV
17%
393 keV
5%
Physiology
Ga-67 acts as an iron analogue. Initially it binds
to transferrin. The complex diffuses through loose
endothelial junctions of capillaries at sites of
inflammation and enters the extracellular fluid.
Leukocytes migrate to sites of inflammation and
degranulate, releasing large quantities of
lactoferrin.
Ga-67 has higher affinity for lactoferrin than
transferrin. Ga-67 also attaches to siderophores of
bacteria. Therefore can be used in leukopenic
patients with bacterial infection and in detecting
sterile abscesses that provoke a leukocyte response.
Areas where Ga-67 normally localizes
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liver (site of highest uptake)
bone marrow
spleen
salivary glands
nasopharynx
lacrimal glands
breast uptake (especially in pregnant and
lactating women)
kidneys and bladder in the first 24 hours faint uptake can still be normal for up to 72
hours
mild diffuse lung uptake at 24 hours or less
Technique
Common injection doses range from 3-6 mCi.
Imaging should not usually be sooner than 24
hours - high background at this time produces
false negatives.
Common Indications of gallium-67
imaging (1)
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Whole-body survey to localize source of fever in
patients with Fever of Unknown Origin (FUO).
Detection of pulmonary and mediastinal
inflammation/infection, especially in the
immunocompromised patient.
Evaluation and follow-up of active lymphocytic
or granulomatous inflammatory processes such
as sarcoidosis or tuberculosis.
Common Indications of gallium-67
imaging (2)
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Diagnosing vertebral osteomyelitis and/or disk
space infection where Ga-67 is preferred over
labeled leukocytes.
Diagnosis and follow-up of medical treatment of
retroperitoneal fibrosis.
Evaluation and follow-up of drug-induced
pulmonary toxicity (e.g. Bleomycin, Amiodarone)
Sarcoidosis
Gallium Tumor Imaging
Gallium tumor localization is likely multifactoral,
but in part related to leaky capillary membranes
in tumors, and the presence of iron-binding
proteins such as ferritin which are found in
increased concentrations in tumors.
Bronchogenic carcinoma
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Squamous cell carcinoma has the highest (gallium
avidity).
adenocarcinoma has the lowest detection rate.
gallium has a overall sensitivity of about 90% for the
detection of primary bronchogenic carcinoma.
Lesions smaller than 1.5 cm are difficult to detect.
Lack of gallium accumulation in a lesion is still
associated with a 24% probability for malignancy.
Hodgkin's lymphoma
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Overall sensitivity for detecting Hodgkins
lymphoma is about 85%, with a specificity of
90%.
Gallium scintigraphy can also be used to predict
patient response to treatment after initiation of
chemotherapy.
nodal uptake of tracer in
the neck and
mediastinum in this
patient with Hodgkins
disease.
Non-Hodgkins Lymphoma
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Gallium sensitivity is reported to be better than
85% for high grade tumors.
Sensitivity for low grade (slow growing) tumors
is poor.
A persistently positive Ga-67 exam after one
cycle of treatment or at midtreatment for nonHodgkins lymphoma is associated with a higher
likelihood for treatment failure, while a negative
scan implies a favorable prognosis.